Conceptual Physics (12th Edition)

by
Hewitt, Paul G.

Published by
Addison-Wesley

ISBN 10:
0321909100

ISBN 13:
978-0-32190-910-7

Chapter 2 - Think and Explain: 47

Answer

Your torso and head's inertia tend to keep them at rest (Newton’s first law.) When your car is struck from behind, the seat pushes your torso forward, but unless you have a headrest that also pushes your head forward, your head won't keep up.
Ouch.